Conventional proton exchange membrane fuel cells (PEMFCs) have been under development for many years. However, PEMFCs still suffer from a number of issues and difficulties. For example, cooling and water management issues typically present challenges in PEMFC development and use. In this regard, fuel cells must be adequately cooled while also not oversaturating the fuel cell or otherwise hindering delivery of hydrogen gas to the catalyst layer in the fuel cell. Similarly, there are concerns for hydrogen safety. For example, if the fuel cell is not adequately cooled, it may overheat, which can be especially problematic with hydrogen gas.
Similarly, hot spot formation in fuel cell stack can cause fuel cell performance degradation. For example, if certain areas of the fuel cell become much warmer or cooler than other areas, the performance of the localized temperature gradients may have decreased performance compared to other areas. This, in turn, can decrease overall fuel cell performance. Therefore, there is a need to provide more efficient and effective cooling in fuel cells.
Many fuel cells, such as PEMFCs, include multiple bipolar plates for providing flow paths for the anode, cathode, coolant, etc. Oftentimes multiple plates are required for each cell in a fuel cell stack to perform these numerous functions. However, by including multiple plates for each cell extra expense and weight are added. In this regard, it may be helpful to minimize the number of bipolar plates used.
As noted above, depending on the fuel cell type, humidification must be provided, such as to keep the membranes used therein adequately humidified during operation. However, such humidifiers can be expensive and heavy. Similarly, the associated pumps and controllers for the humidification, coolant, hydrogen, as well as other gases and liquids have limited lifetimes and typically require regular maintenance. Therefore, decreasing the number of pumps, controllers, and the like may decrease maintenance required on certain types of fuel cells.
In other forms, hydrogen, air, impurities, and the like can accumulate on the catalyst layers in the fuel cell and degrade performance. However, it can be difficult to effectively and efficiently remove those impurities, especially while the fuel cell is in operation. Therefore, it may be helpful to remove impurities and other materials from the catalyst layer and fuel cell generally. This may be especially helpful if done continuously during fuel cell operation.
Further, carbon dioxide can poison fuel cells, such as alkaline fuel cells. Therefore, it may be helpful to remove and/or prevent carbon dioxide therein.